Patent GB-375369-A (GB)
Title: Improvements in electric door operator
IPC: B66B13/08
Filed: 1931-02-24
Abstract: 375,369. Operating lift doors. WAYGOOD-OTIS, Ltd., 54, Fetter Lane, London.-(Otis Elevator Co. ; 260, 11th Avenue, New York, U.S.A.) Feb. 24, 1931, No. 5774. [Class 65 (i).] In a lift door or gate operating mechanism the door is opened by an electric motor and is closed by mechanical means which drives the motor during the closing operation, a circuit being completed, after the closing movement has started, to allow the motor to act as a dynamo, thus checking the speed of closing. The gate 14 is operated by a lever 24 pivoted at 26 and actuated from the motor 16 against the tension of a spring 40 through spur reduction gearing 20, shaft 22, a flexible connection including a chain 29 and spring 31, the chain being engaged by an arm 30 when the shaft is rotated in a counterclockwise direction as seen in Fig. 1. The opening and closing movements are checked by dashpots 32, 34. During the opening movement a spring 76, connected by a chain 72 to a pin 74 on a disc 84 rotating with the shaft 22, is tensioned to provide the reverse drive for the motor, and during the final portion of the movement a second spring 78 is also tensioned by engagement of the abutments 85, 86, Fig. 7, to facilitate the initial reverse rotation of the motor. Associated with the motor 16 is a brake 18 comprising a cone disc 115 on the motor shaft and a slidable non- rotating element 116, which is pressed into braking engagement with the disc 115 by a spring 121, and can be withdrawn either electromagnetically, or by a lever 124 actuated from a foot pedal 132 within the lift cage. The lift shaft doors 15, Fig. 8, are actuated by engagement of a cam rail, carried by the lift, with a bell-crank lever 48, motion of which is communicated to the doors through a link 47 having end universal joints, a link 46, and a toggle system 44. The closing movement is effected by a spring 52, and both opening and closing movements are checked by dash pots 54, 55. The cam rail is maintained in inoperative position while the lift is in motion, and is brought into action when the lift doors are opened by a chain connection to the shaft 22. The electrical control arrangements include switches 39, 56 in the hoisting motor circuit which are opened by the first opening movements of the lift and shaft doors, limit switches such as 98 which open the circuit of the motor 16 towards the end of the opening and closing movements, and a switch 111 which is closed during the intermediate part of the door-closing movement to complete a dynamo circuit through a resistance. This switch is operated by adjustable cams 100, 102, Fig. 6, on a collar 104 on the shaft 22. The motor 16 may be manually controlled, but preferably the control is associated with the hoist control, so that the doors will automatically open when the lift is stopped. The electrical circuit which is described provides also for automatic application and release of the brake 18, for opening the motor circuit bv a thermal switch in the event of overload due to failure of the doors to open, and for switching into the circuit of the motor 16 a resistance should it be necessary to re-open the doors before they have completely closed. This resistance is short-circuited after a predetermined time interval by a dashpot control.